eberhard_wilson10
C70 Overvoltage Faults
Summary of the thread
The 2000 Volvo C70 was experiencing electrical issues, including overvoltage faults and weak battery performance. The problem was suspected to be related to the battery, which, despite being two years old, could cause the alternator to overcompensate, leading to overvoltage. The suggested solution was to have the vehicle diagnosed by a workshop, where it was confirmed that a defective battery was the cause. Replacing the battery resolved the issues.
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4 comment(s)
eberhard_wilson10 (community.author)
The battery is about two years old, so not ancient, but also not brand new. How would a bad battery cause overvoltage, though? I thought it would be the opposite!
dirkheld1
A failing battery can cause the charging system to overcompensate, leading to an overvoltage situation. While other components could cause overvoltage, a weak battery is a likely candidate and is also consistent with your starting issues. Either way, those symptoms point to an electrical issue. I'd suggest getting it properly diagnosed by a workshop.
eberhard_wilson10 (community.author)
Thanks for the tip! I took it to a shop, and you were right – it was a defective battery causing the alternator to work overtime. New battery and everything's running smoothly again. Cost me 290€ Appreciate the help!
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VOLVO
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C70
dirkheld1
Overvoltage huh? Have you checked the battery itself? A heavily discharged or defective battery can sometimes cause these symptoms. How old is it?